As a conventional fuel measurement system, there has been considered a measurement system for measuring a consumption amount of a fuel consumed by an engine using a Coriolis flowmeter.
In this arrangement, since a Coriolis flowmeter can directly measure a mass flow rate of the fuel without being affected by a temperature and pressure of the fuel compared to other types of flowmeters, a Coriolis flowmeter is increasingly used in a fuel consumption amount measurement system in recent years.
However, in the case where the fuel is in a low flow rate region such as a case of measuring a fuel consumption amount of an engine, for example, in a state of idling, measurement values of the Coriolis flowmeter are varied, and there arises a problem that reliability in measuring a fuel consumption amount cannot be obtained.
As a cause of variation in measurement values of the Coriolis flowmeter in a low flow rate region, there is considered a change in elastic force of a pipe (flow tube) inside the Coriolis flowmeter due to a temperature change of the fuel.
Although there is also a measurement system in which a temperature correction of a measurement value is performed by a temperature sensor provided inside a Coriolis flowmeter, this temperature correction is performed using a default value (default value) and therefore the correction accuracy may not be obtained sufficiently due to an instrumental error of the Coriolis flowmeter in some cases.
An error due to the change in elastic force is in a degree of 0.0002 kg/h per 1° C. For example, in the case where a fuel of a large flow rate in a degree of 100 kg/h is measured, since an error value to a measurement value is extremely small, the error can be ignored. Whereas, in the case where a fuel of a small flow rate in a degree of, e.g., 10 kg/h is measured, the error value is large to a measurement value and this error cannot be ignored from the viewpoint of measurement accuracy.
It is noted that, although the configuration provided with the heat exchanger in an upstream side of the Coriolis flowmeter in the system of Japanese Patent JP2006-329990A, since the configuration is not provided with a temperature sensor, this merely indicates that the fuel is cooled in the upstream side of the Coriolis flowmeter.